It was a bunch of stuff. One strand was about me recognizing that my baseline level of stress and anxiety was too high and working to lower that. Another was about improving sleep quality, so I was sharper during the day. A third was recognizing that I was an irresponsible electric light user; I automated my home lights to follow a consistent day-night cycle. [1] And a fourth was around physical exercise; over a few years I went from the stereotypical hates-exercise guy to somebody who regularly runs races.

And possibly related, of course, was that I got older during this period.

[1] https://github.com/wpietri/sunrise